This invention relates to an apparatus and method of deterring excavation of wooden objects such as utility poles by woodpeckers.
Woodpeckers strike objects with their beaks for several purposes. They tap on structures to communicate their presence to other woodpeckers; sequences of taps that are species specific, called drums, are also made as part of territorial and mating behaviors. They make small excavations in wooden objects in their search for insect food items located beneath the surface. Large excavated cavities are made in trees and other similar objects using the beak. These cavities are used for roosting and nesting purposes.
Although woodpeckers historically have tapped on and excavated in trees, man-made structures have become a common target for these types of activities. Woodpeckers can cause damage to objects while engaged in tapping and excavation behaviors. Considerable damage has been reported on wooden utility poles, which woodpeckers utilize in a similar manner to natural trees. Excavations of large woodpecker species, such as the Pileated Woodpecker (Drycopus pileatus) can be larger and cause the larger amounts of damage.
A number of approaches have been tried to deter woodpeckers, particularly the Pileated Woodpecker, from damaging utility poles. The majority are passive deterrents, while others are active (and occasionally automated electronic) deterrents. Passive devices include visual repellents, tactile repellents, chemosensory repellents and physiologic repellents. Visual repellents include balloons with large xe2x80x98eyespotsxe2x80x99 that resembles a predator, raptor models and silhouettes, and iridescent or holographic tape. Visual deterrents are usually mounted on or near utility poles and act as a scaring device. Tactile repellents include polybutene products and roost inhibitors such as spikes or nets. These techniques provide protective measures such as pole wrapping that do not allow woodpeckers to cling to the smooth surface of the plastic wrap. Metal barriers such as wire wrapped around a pole are currently the most widespread and effective technique for preventing woodpecker damage. Chemosensory and physiologic repellents include chemicals such as methyl anthranilate or mesurol. These types of repellents act either on contact or through ingestion of the materials.
A limited number of active devices include auditory repellents (both sonic and ultrasonic), programmable propane xe2x80x98bangersxe2x80x99, and strobe lights. All of these deterrent devices are used to produce xe2x80x98startlexe2x80x99 responses. Auditory repellents include devices with electronically reproduced and broadcasted distress calls, devices that generate very loud sounds by propane explosions and pyrotechnics that are used to scare loafing and roosting birds. Ultrasonic devices are offered as deterrents to roosting and loafing birds, but these devices have no demonstrated utility, probably because most birds are physiologically incapable of detecting ultrasound (i.e., frequencies above 20,000 Hz). At least one deterrent device available in the marketplace is an automated electronic unit.
None of the previously described deterrent methods provided a satisfactory solution for preventing woodpecker damage due to problems with: cost, effectiveness, environmental toxicity, electrical conductivity hazards, devices being bothersome to people or subsequent increases in the difficulty of maintaining pole hardware.
The following patents have been located in a search:
U.S. Pat. No. 4,965,552 issued October 1993 by Price et al entitled xe2x80x9cElectronic Animal Repellant Apparatusxe2x80x9d issued October 1990 discloses a device for animals in general which uses sounds generated by a speaker where the key point is that the sounds are delayed by a random time period after detection to avoid the animal becoming habituated to the sounds.
U.S. Pat. No. 5,986,551 issued November 1999 by Pueyo et al and entitled xe2x80x9cMethod and System for Preservation Against Pesky Birds and Pest Animalsxe2x80x9d discloses a method for dissuading the animals from returning after an initial frightening action.
U.S. Pat. No. 5,956,463 issued September 1999 by Patrick et al entitled xe2x80x9cAudio Monitoring System for Assessing Wildlife Bio-diversityxe2x80x9d discloses a microphone and analysis system for detecting and analyzing bird sounds in the environment.
U.S. Pat. No. 5,243,327 issued September 1993 by Bentz et al entitled xe2x80x9cAudible Alarm for Motion Detection using Dual Mode Transducerxe2x80x9d discloses a transducer which detects the presence of a pet or animal by detecting sounds in the range 20 to 250 Hz generated by the movement of the animal.
U.S. Pat. No. 5,214,619 issued May 1993 by Yoshida entitled xe2x80x9cSupersonic Sound Emission Devicexe2x80x9d discloses a device within a housing for mounting on a pole which is used to generate high frequency sounds with the intention of scaring birds.
U.S. Pat. No. 5,134,592 issued July 1992 by Parra entitled xe2x80x9cMethod and Apparatus for Separating Dolphin from Tunaxe2x80x9d discloses a method of dispersing dolphins by playing sounds from a predator that is the killer whale.
None of these prior patents provide an arrangement suitable to deter the excavation activities of woodpeckers.
This invention is intended to deter woodpeckers from tapping on and excavating within objects.
The invention therefore provides an apparatus for deterring woodpeckers from tapping on and excavating within an object comprising:
a housing having a mounting assembly for mounting the housing on the object so as to receive vibrations therefrom;
a transducer arranged for converting vibrations in the object and into electrical signals, the transducer being arranged to be responsive to the vibrations preferentially over airborne sounds;
a sound transmitter for emitting a deterrent sound externally of the housing;
a memory containing a plurality of audible deterrent sounds which act as a deterrent to the woodpeckers;
and a processing circuit arranged to:
process the electrical signals to discriminate transient woodpecker induced vibrations from long-term background vibrations and to provide an output signal in response to detection of a woodpecker induced vibration;
count the number of output signals within a predetermined time interval;
and, when a predetermined count is reached within the predetermined time interval, to effect actuation of the deterrent by extracting at least one of the sounds from the memory and activating the sound transmitter to transmit the sound.
Preferably the audible deterrent sounds in the memory include a plurality of different sounds at least one of which is generated by woodpeckers and at least one of which is generated by woodpecker predators.
Preferably the processing circuit is arranged to select for sequential actuations different ones of said sounds.
Preferably the processing circuit is arranged such that the audible deterrents generation are halted when the power source voltage is low.
Preferably there is provided a clock providing an indication of time and wherein the processing circuit is arranged such that the audible deterrents generation are halted at certain times of day or days of year.
Preferably the processing circuit is arranged such that the audible deterrents generation are delayed after the predetermined count is reached for a predetermined delay period.
Preferably the processing circuit is arranged such that the audible deterrents generation are limited to a certain number within a predetermined time period to avoid repeated generations from draining the power source.
Preferably the processing circuit is arranged such that the signals are discriminated by comparing a long-term average of the signal energy and a short term average of signal energy.
Preferably the processing circuit is arranged such that the signals are discriminated by comparing short-term average signal energy which must exceed the long term average signal by a threshold value amount.
Preferably the processing circuit is arranged such that the short-term average signal energy is determined using a peak detector with a short time constant and the long term average signal is determined using a peak detector with a long time constant.
Preferably a piezoelectric transducer is used to convert vibrations into electrical signals which is mounted within the housing and arranged to receive vibrations directly from the connection between the housing and the object.
Preferably the transducer is a contact microphone which is mounted within the housing and arranged to receive vibrations directly from the connection between the housing and the object.
Preferably the processing circuit is arranged such that periodically after a predetermined time period information is stored in a memory of the number of detected vibrations along with an indication of the day and time.
Preferably the processing circuit is arranged such that the information stored includes whether the deterrent was actuated in the time period.
Preferably the housing has a cover over an upper wall thereof to reduce spurious vibrations caused by impact of objects on the housing.
Preferably the cover is flexible.
Preferably there is provided on the housing a data output element such that data can be transferred from the memory to a remote location.
Preferably there is provided on the housing a light output element visible from an observer on the ground adjacent the object such that data can be transferred from the memory to the observer and wherein the processing circuit is arranged such that the light output element is actuated each time a predetermined count is reached whereby an observer can actuate the output by tapping on the object.
Preferably the sound emitted is directed by a baffle mounted on the housing so as to direct the sound from the speaker along the object to the woodpecker on the object.
Preferably the processing circuit is arranged such that it is partially deactivated and deactivates components of the circuit for a predetermined time period and is reactivated periodically to check for detected vibrations.
The arrangement thus preferentially detects vibration in the object rather than the presence of air-borne sounds. Based on analysis of the vibration, sounds are emitted that deter the woodpeckers.
The electronic circuitry is housed within a weather-resistant housing. The housing is protected from spurious vibrations induced by falling precipitation by a shield or foam covering. The housing is mounted on the object to be protected from woodpecker activity.
Several commonly known aspects of animal behavior are relevant in the development of a new means for deterring woodpeckers from tapping on and excavating objects. First, woodpeckers tap, drum and make vocal calls to communicate. Secondly, woodpeckers change their behavior in response to the sounds of their own species (taps, drums and calls) as well as to key predators such as hawks. Thirdly, animals tend to become habituated to, that is to say respond in less to, stimuli (e.g. sounds) which occur repeatedly over a long time period.
Vibrations can be detected electronically by mounting a vibration-sensitive transducer to an object. Analysis of the resulting signal produced by the transducer can be used to determine whether or not certain events have occurred on or within the object. Such events can be counted, their frequency of occurrence per unit of time determined and the results stored (logged) or acted upon.
Although active deterrents for wildlife exist, there appears to be no device that is targeted specifically for detecting tapping or excavation of a woodpecker on an object, logging its activity pattern and subsequently acting to deter the woodpecker based on its known behaviors. By performing some or all of these functions, this invention overcomes many of the problems associated with currently available techniques.
The invention also includes a transducer (vibration sensor or microphone) sensitive to vibration, an amplifier to amplify the transducer signal, and a means to discriminate signals from xe2x80x98tap-likexe2x80x99 vibrations based on their amplitude from signals produced by more constant xe2x80x98backgroundxe2x80x99 vibrations. When a xe2x80x98tapxe2x80x99 is detected, an event is counted.
The invention maintains counts of the number of events that occur within a given time period. The count can be stored (logged) in a non-volatile memory along with time and date information for later retrieval.
When a certain number of events are counted within a time interval, the device activates circuitry to produce one of a series of sounds. Activation can be modified in a number of ways. Activation can be delayed for a set period of time. Activation may be inhibited based on time of day or day of year. Activation may be inhibited based on the condition of the power source.
Sounds are based on recordings of natural sounds so that they are intended to sound natural to woodpeckers, and they sound natural and are presumed not to be as irritating to humans as are unnatural sounds. Sounds include sounds made by woodpeckers and their predators. Each time the device is activated, one of several sounds is produced to reduce habituation. Sounds are played in sequence for a duration equal to their length in time. The device stores sound data digitally in a non-volatile memory. Digital data is converted to an analog form by a digital to analog converter (DAC), is low-pass filtered, is amplified by a power amplifier and is converted to audible sound by one or more audio transducers such as speakers. The direction in which the sound is emitted may be modified with a baffle to improve effectiveness.
Although the invention could be powered by any reasonable power source, the preferred method utilizes a solar panel (photo-voltaic array or module) to charge a rechargeable battery.
The device contains a means for setting parameters of activation and operation and a means for setting and determining time of day and/or day of year.
The device may include a provision for serial data communications between it and an external terminal device. Serial communications are utilized for reading and writing parameter values and data.